diff --git a/dev-java/lz4-java/Manifest b/dev-java/lz4-java/Manifest
new file mode 100644
index 0000000000000..47194c6142a14
--- /dev/null
+++ b/dev-java/lz4-java/Manifest
@@ -0,0 +1 @@
+DIST lz4-java-1.8.0.tar.gz 1069398 BLAKE2B 02ee363fc42eeeade01f04649416dd874513f4517264c6e1b6474d64e8b81e2ee9ff1f55e51b508608929e8d78cb30e98d929cc4a118c03f86b0e69bae237e8a SHA512 ae78748d984d2ede18018d5e9ae6aee0d5fe6ac8b56d717f863968cfad6e9f85b62305692345ba16002bee68278e87a0364aa98aeb92e2af6dc169e5d5b612d4
diff --git a/dev-java/lz4-java/files/lz4-java-1.8.0-Makefile b/dev-java/lz4-java/files/lz4-java-1.8.0-Makefile
new file mode 100644
index 0000000000000..8d59aa8df84a5
--- /dev/null
+++ b/dev-java/lz4-java/files/lz4-java-1.8.0-Makefile
@@ -0,0 +1,47 @@
+# Gentoo custom Makefile for the JNI portion of lz4-java
+#
+# Adapted from the logic for target "compile-jni" in build.xml,
+# but uses lz4 installed on the system.  This Makefile respects
+# custom CFLAGS and LDFLAGS settings, whereas build.xml does not.
+
+# Java system properties read by build.xml
+PLATFORM ?= linux
+SRC ?= src
+BUILD ?= build
+JAVA_HOME ?=
+# Requires lz4-java-*-print-os-props.patch
+OS_ARCH := $(shell ant os-props 2>&1 > /dev/null && \
+		grep 'os\.arch=' os.properties | sed -e 's/os\.arch=//')
+
+MKDIR_P = mkdir -p
+
+SRC_DIR := $(SRC)/jni
+OBJS_DIR_PREFIX := $(BUILD)/objects
+OBJS_DIR := $(OBJS_DIR_PREFIX)/$(SRC_DIR)
+OUT_DIR := $(BUILD)/jni/net/jpountz/util/$(PLATFORM)/$(OS_ARCH)
+
+SRC_FILES := $(wildcard $(SRC_DIR)/*.c)
+OBJS := $(addprefix $(OBJS_DIR_PREFIX)/,$(SRC_FILES:.c=.o))
+SONAME = liblz4-java.so
+
+# C compiler arguments may be obtained by running 'ant -v compile-jni',
+# as long as dev-java/cpptasks is in the classpath
+CFLAGS := -fPIC $(CFLAGS)
+# '--as-needed' causes test failure
+LDFLAGS := $(LDFLAGS) -Wl,--no-as-needed
+
+$(OUT_DIR)/$(SONAME): $(OBJS) | $(OUT_DIR)
+	$(CC) $(CFLAGS) -shared $(LDFLAGS) -Wl,-soname,$(SONAME) -o $@ -llz4 $^
+
+$(OBJS_DIR_PREFIX)/%.o: %.c | $(OBJS_DIR)
+	$(CC) $(CFLAGS) -c -o $@ \
+		-I$(JAVA_HOME)/../include -I$(JAVA_HOME)/../include/$(PLATFORM) \
+		-I$(JAVA_HOME)/include -I$(JAVA_HOME)/include/$(PLATFORM) \
+		-I$(BUILD)/jni-headers \
+		$<
+
+$(OUT_DIR):
+	$(MKDIR_P) $@
+
+$(OBJS_DIR):
+	$(MKDIR_P) $@
diff --git a/dev-java/lz4-java/files/lz4-java-1.8.0-gentoo-classpath.xml b/dev-java/lz4-java/files/lz4-java-1.8.0-gentoo-classpath.xml
new file mode 100644
index 0000000000000..2392679c4a69b
--- /dev/null
+++ b/dev-java/lz4-java/files/lz4-java-1.8.0-gentoo-classpath.xml
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<project name="gentoo-classpath">
+    <path id="mvel.classpath">
+        <pathelement path="${gentoo.classpath}" />
+    </path>
+</project>
diff --git a/dev-java/lz4-java/files/lz4-java-1.8.0-print-os-props.patch b/dev-java/lz4-java/files/lz4-java-1.8.0-print-os-props.patch
new file mode 100644
index 0000000000000..d4363b6853e4c
--- /dev/null
+++ b/dev-java/lz4-java/files/lz4-java-1.8.0-print-os-props.patch
@@ -0,0 +1,31 @@
+From b8d50d44ba1c0e4b5bf297f7499ad0fb5b82706e Mon Sep 17 00:00:00 2001
+From: Yuan Liao <liaoyuan@gmail.com>
+Date: Wed, 19 Jan 2022 10:09:14 -0800
+Subject: [PATCH] build.xml: Add target that prints JVM system properties os.*
+
+The Gentoo custom JNI Makefile needs some of those properties.
+
+Signed-off-by: Yuan Liao <liaoyuan@gmail.com>
+---
+ build.xml | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/build.xml b/build.xml
+index b7940ab..96e52ea 100644
+--- a/build.xml
++++ b/build.xml
+@@ -62,6 +62,11 @@
+     <javaversion atleast="10"/>
+   </condition>
+ 
++  <target name="os-props"
++    description="echo values of JVM system properties os.* to file os.properties">
++    <echoproperties prefix="os." destfile="os.properties" />
++  </target>
++
+   <target name="clean" description="clean working copy">
+     <delete dir="${build}" />
+     <delete dir="${dist}" />
+-- 
+2.34.1
+
diff --git a/dev-java/lz4-java/files/lz4-java-1.8.0-skip-ivy.patch b/dev-java/lz4-java/files/lz4-java-1.8.0-skip-ivy.patch
new file mode 100644
index 0000000000000..26c09e147072c
--- /dev/null
+++ b/dev-java/lz4-java/files/lz4-java-1.8.0-skip-ivy.patch
@@ -0,0 +1,91 @@
+From 95ae85542f39cecd1af6a3e661ad6120195d2304 Mon Sep 17 00:00:00 2001
+From: Yuan Liao <liaoyuan@gmail.com>
+Date: Mon, 20 Dec 2021 09:57:31 -0800
+Subject: [PATCH] build.xml: Skip Ivy logic and use Gentoo classpath
+
+Signed-off-by: Yuan Liao <liaoyuan@gmail.com>
+---
+ build.xml | 22 +++++++---------------
+ 1 file changed, 7 insertions(+), 15 deletions(-)
+
+diff --git a/build.xml b/build.xml
+index b7940ab..ff321c6 100644
+--- a/build.xml
++++ b/build.xml
+@@ -20,6 +20,8 @@
+     xmlns:junit4="antlib:com.carrotsearch.junit4"
+     xmlns:mvn="antlib:org.apache.maven.artifact.ant">
+ 
++  <import file="gentoo-classpath.xml" />
++
+   <property name="src" location="src"/>
+   <property name="build" location="build"/>
+   <property name="dist"  location="dist"/>
+@@ -81,8 +83,6 @@
+   </target>
+ 
+   <target name="install-cpptasks" unless="cpptasks.available">
+-    <ivy:cachepath organisation="ant-contrib" module="cpptasks" revision="1.0b5"
+-      inline="true" conf="default" transitive="true" pathid="cpptasks.classpath"/>
+     <taskdef uri="antlib:net.sf.antcontrib.cpptasks" resource="net/sf/antcontrib/cpptasks/antlib.xml" classpathref="cpptasks.classpath"/>
+     <property name="cpptasks.available" value="true"/>
+   </target>
+@@ -117,22 +117,14 @@
+ 
+   <target name="init">
+     <tstamp />
+-    <ivy:resolve file="${ivy.xml.name}" conf="test" />
+-    <ivy:retrieve />
+   </target>
+ 
+   <target name="install-junit4" depends="init" unless="junit4.available">
+-    <taskdef uri="antlib:com.carrotsearch.junit4">
+-      <classpath>
+-        <fileset dir="${lib}" includes="*.jar" />
+-      </classpath>
+-    </taskdef>
++    <taskdef uri="antlib:com.carrotsearch.junit4" resource="com/carrotsearch/junit4/antlib.xml" classpath="${gentoo.classpath}"/>
+     <property name="junit4.available" value="true" />
+   </target>
+ 
+   <target name="generate-sources" depends="init">
+-    <ivy:cachepath organisation="org.mvel" module="mvel2" revision="2.3.2.Final"
+-      inline="true" conf="default" transitive="true" pathid="mvel.classpath"/>
+     <mkdir dir="${build}/java" />
+     <java
+       fork="true"
+@@ -244,12 +236,12 @@
+     <pathelement path="${build}/classes" />
+     <pathelement path="${build}/unsafe-classes" />
+     <pathelement path="${build}/generated-classes" />
+-    <fileset dir="lib" includes="*.jar" />
++    <pathelement path="${gentoo.classpath}" />
+   </path>
+ 
+   <path id="compile.tests.classpath.with.jar">
+     <pathelement path="${lz4-java.jar}" />
+-    <fileset dir="lib" includes="*.jar" />
++    <pathelement path="${gentoo.classpath}" />
+   </path>
+ 
+   <path id="test.classpath">
+@@ -260,14 +252,14 @@
+     <pathelement path="${build}/unsafe-classes" />
+     <pathelement path="${build}/generated-classes" />
+     <pathelement path="${build}/test-classes" />
+-    <fileset dir="${lib}" includes="*.jar" />
++    <pathelement path="${gentoo.classpath}" />
+   </path>
+ 
+   <path id="test.classpath.with.jar">
+     <pathelement path="${lz4-java.jar}" />
+     <pathelement path="${src}/test-resources" />
+     <pathelement path="${build}/test-classes" />
+-    <fileset dir="${lib}" includes="*.jar" />
++    <pathelement path="${gentoo.classpath}" />
+   </path>
+ 
+   <target name="test" description="run tests">
+-- 
+2.32.0
+
diff --git a/dev-java/lz4-java/lz4-java-1.8.0.ebuild b/dev-java/lz4-java/lz4-java-1.8.0.ebuild
new file mode 100644
index 0000000000000..15c53d9470491
--- /dev/null
+++ b/dev-java/lz4-java/lz4-java-1.8.0.ebuild
@@ -0,0 +1,101 @@
+# Copyright 2021-2022 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+JAVA_PKG_IUSE="doc source test"
+MAVEN_ID="org.lz4:lz4-java:1.8.0"
+
+inherit java-pkg-2 java-ant-2 toolchain-funcs
+
+DESCRIPTION="LZ4 compression for Java"
+HOMEPAGE="https://github.com/lz4/lz4-java"
+SRC_URI="https://github.com/lz4/lz4-java/archive/refs/tags/${PV}.tar.gz -> ${P}.tar.gz"
+
+LICENSE="Apache-2.0"
+SLOT="0"
+KEYWORDS="~amd64 ~arm ~arm64 ~ppc64 ~x86"
+
+# Tests require com.carrotsearch.randomizedtesting:junit4-ant, which is yet to
+# be packaged.  Some extra steps are required before running the tests:
+# 1. Download junit4-ant 2.7.x from https://mvnrepository.com/artifact/com.carrotsearch.randomizedtesting/junit4-ant
+# 2. Set EANT_GENTOO_CLASSPATH_EXTRA to the path to junit4-ant-2.7.*.jar
+# 3. arm, arm64 and ppc64 only: Install test dependencies that are unkeyworded
+# 4. Set ALLOW_TEST="all"
+RESTRICT="test"
+
+CDEPEND="
+	app-arch/lz4
+"
+
+# The version requirement on mvel is strict; mvel-2.4.* generates source files
+# incorrectly, which causes build failure of this package
+DEPEND="
+	>=virtual/jdk-1.8:*
+	dev-java/mvel:2.3
+	dev-libs/xxhash
+	test? (
+		dev-java/junit:4
+		!arm? ( !arm64? ( !ppc64? (
+			dev-java/randomized-runner:0
+		) ) )
+	)
+	${CDEPEND}
+"
+
+RDEPEND="
+	>=virtual/jre-1.8:*
+	${CDEPEND}
+"
+
+# Ant is only needed to generate JNI headers;
+# the JNI shared object will be built by the custom Makefile
+EANT_BUILD_TARGET="compile-java generate-headers"
+EANT_DOC_TARGET="docs"
+EANT_EXTRA_ARGS="-Djava.io.tmpdir=${T}"
+EANT_TEST_GENTOO_CLASSPATH="randomized-runner"
+
+pkg_setup() {
+	java-pkg-2_pkg_setup
+	local build_only_cp="$(java-pkg_getjars --build-only mvel-2.3)"
+	if [[ -z "${EANT_GENTOO_CLASSPATH_EXTRA}" ]]; then
+		EANT_GENTOO_CLASSPATH_EXTRA="${build_only_cp}"
+	else
+		EANT_GENTOO_CLASSPATH_EXTRA+=":${build_only_cp}"
+	fi
+}
+
+src_prepare() {
+	eapply "${FILESDIR}/${P}-print-os-props.patch"
+	eapply "${FILESDIR}/${P}-skip-ivy.patch"
+	cp "${FILESDIR}/${P}-Makefile" Makefile || die "Failed to copy Makefile"
+	cp "${FILESDIR}/${P}-gentoo-classpath.xml" gentoo-classpath.xml ||
+		die "Failed to copy Gentoo classpath injection XML"
+	java-pkg-2_src_prepare
+	rm -r src/resources || die "Failed to remove pre-built shared libraries"
+}
+
+src_compile() {
+	java-pkg-2_src_compile
+	emake CC="$(tc-getCC)" JAVA_HOME="${JAVA_HOME}"
+	# JNI has already been built by the Makefile at this point
+	# Also pretend cpptasks is available, which is required by build.xml
+	EANT_EXTRA_ARGS+=" -Dcpptasks.available=true -Dskip.jni=true"
+	# Manually call 'ant jar' to include the JNI shared object in JAR
+	eant jar -f "${EANT_BUILD_XML}" ${EANT_EXTRA_ARGS}
+}
+
+src_test() {
+	java-pkg-2_src_test
+}
+
+src_install() {
+	java-pkg_newjar 'dist/${ivy.module}.jar'
+	java-pkg_doso $(find build/jni -name "*.so")
+	use doc && java-pkg_dojavadoc build/docs
+	# Ant project's 'sources' target generates a source JAR rather than a Zip
+	# archive; we simply let java-utils-2.eclass create the source Zip archive
+	# from the same source directories the 'sources' target would access
+	# https://github.com/lz4/lz4-java/blob/1.8.0/build.xml#L323-L330
+	use source && java-pkg_dosrc src/java/* src/java-unsafe/*
+}
diff --git a/dev-java/lz4-java/metadata.xml b/dev-java/lz4-java/metadata.xml
new file mode 100644
index 0000000000000..576cd0ee41f10
--- /dev/null
+++ b/dev-java/lz4-java/metadata.xml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
+<pkgmetadata>
+	<maintainer type="project">
+		<email>java@gentoo.org</email>
+		<name>Java</name>
+	</maintainer>
+	<upstream>
+		<remote-id type="github">lz4/lz4-java</remote-id>
+	</upstream>
+</pkgmetadata>